1. Technical Field
The present invention relates to a relative angle sensing device and an electric power steering apparatus.
2. Related Art
Recently, there has been suggested a device for sensing a relative rotation angle between two rotary shafts coaxially arranged.
For example, a device described in Japanese Patent Application Laid Open Publication No. 2007-187589 is provided with: two magnetism collecting rings that are arranged around the outer periphery of a magnetic circuit formation component contained in a first rotating body and a second rotating body coaxially connected by a torsion bar so as to be isolated in an axial line direction, and collect a magnetic flux generated by the magnetic circuit formation component; a sensing part that senses torque applied to the first rotating body on the basis of the magnetic flux density collected by each of the magnetism collecting rings; a holding ring that holds the magnetism collecting rings and the sensing part, and has an attachment part attached to a housing, at the outer peripheral portion thereof; and a conductive wire that is connected to the sensing part. The sensing part is configured to change a sensed signal in accordance with change of the magnetic flux density generated between convex pieces of the magnetism collecting rings, and the sensed signal is given to a control part formed by using a microprocessor, through the conductive wire.